The present invention relates to an asynchronous transfer mode (ATM) transmission system that performs transmission process by distributing an asynchronous transfer mode (hereinafter, sometimes abbreviated to ATM) transmission processing function to plural electronic circuit packages and forming routes between the electronic circuit packages. Particularly, the present invention relates to an ATM system that can flexibly vary the transmission route while the configurations of various process functions are being managed. Furthermore, the present invention relates to an ATM transmission method.
Generally, ATM transmission is executed by plural process functions. In an ATM transmission system, the process functions are built in various kinds of electronic circuit packages. An ATM transmission processing section is configured by serially arranging the electronic circuit packages to execute sequentially signal processes.
Each electronic circuit package packages only part of a series of transmission processes in the processing section. It is important that the parts are serially connected to make a set of process functions so that a specific ATM cell can be processed. In order to meet such a demand, various types of ATM transmission systems have been proposed.
FIG. 8 is a block diagram showing the configuration of a conventional ATM switching system.
The ATM switching system is disclosed in JA-143135/1995. Plural basic switch modules 110, . . . , 110 are connected to the connection switch module 120.
The connection switch module 120 has an output bus 130 connected to the basic switch modules 110. A set of plural output lines 131, . . . ,131 forming the output bus 130 acts as one output line bundle 132. In the output line bundles 132, output lines 131, . . . ,131 unused are used to transfer ATM cells, in place of the output lines 131, . . . , 131 in the same set.
When the traffic on one output line 131 becomes heavy because of a rush of ATM cells, the heavy traffic is distributed to unused output lines 131 in the same set. Thus, the effective throughput of the connection switch module 120 can be improved.
The connection switch module 120 has a buffer function by which excessive traffic acceptable by each of output lines 131, . . . , 131 can be temporarily held. Since the excessive traffic is distributed to unused output lines 131, it is not needed to hold temporarily the excessive traffic. Hence, the maximum buffer function of the connection switch module 120 can be reduced.
The traffic allowable in the same set increases because of the is maximum buffer function is maintained. Hence the connection switch module 120 can expand its switching capacity by the remaining buffer function. The connection switch module 120 can expand its switching capacity corresponding to the increment by increasing connectable basic switch modules 110.
The connection switch model 120 can expand its switching capacity or add basic switch modules, without increasing hardware amount such as buffer function.
However, when the ATM transmission process function in the conventional ATM transmission system is changed or added, there have been the following problems:
Firstly, since the object to be expanded is limited to the basic switch modules 110, the process function in the ATM transmission cannot be varied and added arbitrarily and flexibly in units of electronic circuit packages.
Secondary, since the premise is that plural output lines 131, . . . , 131 are aggregated as one output line bundle 132 to the same basic switch module, the electronic circuit package is fixed inevitably. Hence, an arbitrary connection configuration cannot be realized that an ATM transmission process function is varied and added later.